1. Field of the Invention
The present invention relates to a process for manufacturing balls made of a ceramic material. The present invention further relates to an apparatus for implementing the process of manufacturing the balls of the ceramic material. The balls produced are suitable for use in ballpoint pens, for example.
2. State of the Prior Art
A process for manufacturing balls made of a ceramic material is described in U.S. Pat. No. 4,621,936, which patent is incorporated herein by reference. A fluent ceramic material is conveyed in a free-flowing state as a slip from a slip storage tank to at least one nozzle. The material issues from the nozzle drop-by-drop into a gelatinizing solution, in which solution the material sinks while gelatinizing. In this patent, the ball diameter capable of being manufactured in the process is a function of the diameter of the nozzle. In order to achieve different ball diameters, the nozzles have to be changed. This is time consuming. In addition, only ball diameters below 3.5 millimeters can be achieved with the drip method set forth in U.S. Pat. No. 4,621,936.
Balls of a larger diameter can be manufactured in a known molding process. However, balls manufactured in the known molding process are less round than balls manufactured using the drip method. Therefore the molded balls have to be reground if exacting requirements are placed on their roundness.
In both the drip method and in the molding process, a number of balls are usually shaped at the same time. However, in both methods, the rate of production is limited. In the drip method according to U.S. Pat. No. 4,621,936, the drip rate cannot simply be raised, as the drip rate also has an effect on the ball diameter. In the molding process, the rate of production is limited by the sequence of steps involved in the molding operation.